Preliminary study of the characteristics of a high Mg containing Al-Mg-Si alloy

Abstract

An Al-20Mg-4Si high Mg containing alloy has been produced and its characteristics investigated. The as-cast alloy revealed primary Mg 2Si particles evenly distributed throughout an α-Al matrix with a β-Al 3Mg 2 fully divorced eutectic phase observed in interdendritic regions. The Mg 2Si particles displayed octahedral, truncated octahedral, and hopper morphologies. Additions of Sb, Ti and Zr had a refining influence reducing the size of the Mg 2Si from 52 ± 4 μm to 25 ± 0.1 μm, 35 ± 1 μm and 34 ± 1 μm respectively. HPDC tensile test samples could be produced with a 0.6 wt.% Mn addition which prevented die soldering. Solution heating for 1 hr was found to dissolve the majority of the Al 3Mg 2 eutectic phase with no evidence of any effect on the primary Mg 2Si. Preliminary results indicate that the heat treatment has a beneficial effect on the elongation and the UTS.